Really useful video. I like the addition of the felt and riverside brush to strengthen the river sections whilst maintaining flexibility for down hill runs.
Of course the same method is a great way to create a flexible road/path system. Just make the the width slightly less (but that is up to you) and use brown and greys instead of the blue to colour.
Generally these will sit better on table than card and are not as likley to blow around as felt
Didnt find any contact possibiltiy to Greg, so i can only revise to my
thread here, for magnetic "Turn-Clock-Control" counter ;)